A critical step in biomolecular drug manufacture is the separation of “proteins of interest”, the active elements in drugs, from other materials. This separation step is mostly based on chromatography technology with suitable separation media. The most widely used separation media in chromatography is polymer microparticles such as polysaccharide beads.
Polysaccharide beads are traditionally produced by emulsion processes, in which an aqueous solution of the polysaccharide is poured into a hydrophobic solvent in a stirring vessel. As the polysaccharide solution and the hydrophobic solvent are immiscible with each other, agitation turns the two liquids into an emulsion with the polysaccharide solution as droplets suspended in the hydrophobic solvent. A water-in-oil emulsifier soluble in the hydrophobic solvent may be added to stabilize the droplets so they do not coalesce into larger ones. The emulsion is then cooled to cause the droplets to gel to form microparticles of the polysaccharide. As the emulsion processes involve use of large amount of environmentally unfriendly solvents such as toluene, intensive washing is needed to remove the solvents in the polysaccharide microparticles in order to meet the downstream application requirement.
As the industry is facing more and more stringent environmental requirements, there is a need for a more environmentally friendly process of making microparticles.